Fretted finger board for stringed musical instruments and method of making the same



Aug. 25, 1953 M. MACCAFERRI FRETTED FINGER BOARD FOR STRINGED MUSICALINSTRUMENTS AND METHOD OF MAKING THE SAME Filed July 3, 1950 v 5Sheets-Sheet l ATTORNEY;

M. MACCAFERRI NGER BOARD F Aug. 25, 1953 FRETTED OR STRINGED MUSICALINSTRUM S AND METHOD OF MAKING THE SAME Filed July 5, 1950 5Sheets-Sheet 2 A vm q MOW ATTORNEY.5

1953 M. MACCAFERRI 2,649,323

FRETTED FINGER BOARD FOR STRINGED MUSICAL INSTRUMENTS AND METHOD OFMAKING THE SAME Filed July 3, 1950 5 Sheets-Sheet 5 a m L MMNAHNLN m N@MRN m W wwm 0N .sm W3 M W T wnm NW k a O ON a ATTORNEYJ Aug. 25, 1953M. MACCAFERRI 2,649,828

FRETTED FINGER BOARD FOR STRINGED MUSICAL INSTRUMENTS AND METHOD OFMAKING THE SAME Filed July 3, 1950 5 Sheets-Sheet 4 11m 41m) flfll 4111)an) 1N VENTOR;

ATTORNEYJ 1953 MACCAFE I 2,649,828

M FR ED FINGER B D F S INGED MU AL IN UMENTS AND THOD MAKING THE MEFiled July 3, 1950- 1 5 Sheets-Sheet 5 Patented Aug. 25, 1953 FRETTEDFINGER BOARD FOR STRINGED MUSICAL INSTRUMENTS AND METHOD OF MAKING THESAME Mario Maccaferri, Rye, N. Y.

Application July 3, 1950, Serial No. 179,111

12 Claims. 1

My present invention relates to certain improvements in fretted fingerboards for stringed musical instruments, and the nature and objects ofthe invention will be readily understood and recognized by those skilledin the several arts involved in the light of the following explanationand detailed description of the accompanying drawings illustrating whatI at present consider to be the preferred embodiments of finger boards,and the preferred steps and sequences thereof constituting the method ofthe invention, from among other forms, expressions, embodiments,modifications, designs, constructions and combinations of finger board,as well as other steps and sequences thereof for carrying out themethod, of which the invention is capable within the broad spirit andscope thereof as defined by the appended claims.

This application constitutes a continuation-inpart of my applicationSerial No. 149,741, filed March 15, 1950, now Patent No. 2,597,154,dated May 20', 1952, for Improvements in Stringed Musical Instruments.

The invention is concerned generally with various types and forms ofstringed musical instruments characterized by a resonant body or bellhaving a sounding board, with a fretted finger board carried by a neckextended from one end of the body, and vibratory strings secured betweentuning pegs or keys at the other end of the finger board and a bridge onthe body, the strings being located in positions extended over and alongthe finger board. In playing such types of stringed musical instruments,each string is capable of producing when vibrated any :1."

one of a series of notes within a range as determined by the particularstring and the number and spacing of the frets of the finger boardtherebeneath, through so-called stopping of a string. The player carriesout such stopping by pressing the string against the finger board byplacing a finger on the string in position at the rear side of theproper fret to cause the string when so stopped, to produce whenvibrated the desired note of the series of notes capable of pro ductionfrom such string. The strings on such an instrument when unstopped oropen are completely out of contact with the series of frets of thefinger board between the string divider at the outer end of the fingerboard and the bridge on the body to which the strings are attached.Hence, for any given string of predetermined note producingcharacteristics in a given instrument, the construction and formationand the spacing of the frets relative to each other 2 and with respectto the length of the string between its points of constant contact atthe string divider and the bridge are critical factors which determinethe precision of note production and the resulting musical efficiencyand perfection of the instrument.

It is to the improvement of the design, arrangement and construction andof the functional and musical efficiency of the fretted finger boardsfor such types of stringed musical instruments that my present inventionis primarily directed.

One of the main objects of the invention is to increase the efficiencyand accuracy with which a player may execute the finger stopping of thestrings on a fretted finger board, and to enable the attainment fromsuch stopping, of precision in the pitch, tone and timbre of the notesproduced from the vibration of the stopped strings, through a design andconstruction of the fretted finger board and by a precision of spacingof the frets relative to the board, to each other and to the effectiveover-all length of the strings. A further object is to provide a noveland efiicient system of fret spacing for such fretted finger boards.Another object is to provide a fretted finger board in which both thebody or base board and the frets thereon are formed of moldedthermoplastic materials.

Another object is to provide such an all-plastic, fretted finger boardin which the frets are formed of molded thermoplastic material of acolor contrasting with the color of the board or body.

Another object is to provide such an all plastic finger board in whichthe molded thermoplastic material from which the frets are formed hascertain different characteristics from the thermoplastic material fromwhich the board or body is formed.

Another object is to provide such an all-plastic fretted finger board inwhich the frets are formed of a molded thermoplastic material havingcertain metallic characteristics and simulating a metal in appearance.

A further object is to provide a fretted finger board provided at itsinner or body end with a novel design and construction of fret carryingextension to thereby increase the note range of at least certain of thestrings of the instrument in which such a board is embodied.

A further object is to provide an improved design and construction ofthe so-called nut or string divider at the outer end of a fretted fingerboard and of a master fret constituting the first of the series of fretsof the board and engaging and supporting from the string divider thestrings of the instrument.

And a further object is to provide a novel bonding and strengtheningarrangement for securing the frets to and on the body of the board wheneither completely overmolded on the outer face of the board or partiallyinlaid or inset therein, so that the frets become in effect one partwith the body of the board.

With the foregoing general objects, features and results in view, aswell as certain others which will be readily recognized by those skilledin the art from the following detailed description and explanation, myinvention consists in certain novel features in design, construction,materials and arrangements of parts and in combination thereof, as wellas in the novel steps and sequences constituting the method of theinvention, all as will be more fully and particularly hereinafterreferred to and described.

Referring to the accompanying drawings, in which similar referencecharacters refer to corresponding parts and elements throughout theseveral figures thereof:

Fig. 1 is a view in top plan of a stringed instrument of the ukuleletype having a finger board of my invention embodied therein.

Fig. 2 is a view in side elevation of the ukulele instrument of Fig. 1.

Fig. 3 is an enlarged view in top plan of the complete finger boardremoved from the instrument of Figs. 1 and 2.

Fig. 4 is a plan view, more or less schematic, of the mold cavity of oneof the mold sections of an injection mold for forming the base or barconstituting the body of the finger board of Fig. 3.

Fig. 5 is a longitudinal section taken as on the line 5--5 of Fig. 4,through the complete mold in closed position and including the moldsection of Fig. 4, with a completed finger board forming bar or bodytherein.

Fig. 6 is a longitudinal section similar to Fig. 5, but taken as on theline 56 of Fig. 4.

Fig. '7 is a transverse sectional view through the closed mold of Figs.5 and 6, and the completed board body therein, taken as on the line l!of Fig. 4.

Fig. 8 is a transverse sectional View similar to Fig. '7, but taken ason the line 8--B of Fig. 4.

Fig. 9 is a view in end elevation of the completed finger board bodyformed in the mold of Figs. 5 and 6, the mold being indicated in dottedoutline.

Fig. 10 is a view in top plan of one of the mold sections of the moldfor overmolding the frets on the finger board produced in the molds ofFigs. 4 to 9, a finger board body being shown inserted in position inthe mold section preparatory to closing the mold with the mating sectionthereof shown in Figs. 11 to 14.

Fig. 11 is a longitudinal section through the fret forming mold with themold sections closed, at the completion of the molding operation, andshowing the finger board with the frets and fret bonding ribs and runneror spine therefor molded and bonded thereon, the section having beentaken as on the line H-ll of Fig. 10.

Fig. 12 is a longitudinal sectional view similar to Fig. 11, but takenas on the line I 2--i2 of Fig. 10.

Fig. 13 is a transverse sectional view through the closed mold of Figs.11 and 12, with its contained, completed finger board, and taken as onthe line 13-13 of Fig. 10.

Fig. 14 is a transverse sectional view similar to Fig. 13, but taken ason the line 14-44 of Fig. 10.

Fig. 15 is a view in top plan, more or less schematic, of the moldsection and its cavity, for molding the underside of a modified form offinger board body or bar preparatory to the overmolding of the fretsthereon in a second mold.

Fig. 16 is a view in top plan of the completed finger board of themodified form with the frets overmolded thereon and bonded thereto.

Fig. 17 is a longitudinal sectional view taken as on the line l'l-H ofFig. 15, through the closed mold which includes the mold section of Fig.15, with a completed finger board body therein prior to opening of themold.

Fig. 18 is a view in transverse section through the closed mold of Fig.17, with the finger board body therein, taken as on the line IBI8 ofFig. 15.

Fig. 19 is a transverse sectional view similar to Fig. 18, but taken ason the line 19-19 of Fig. 15.

Fig. 20 is a perspective view taken from the underside of the completedmodified form of finger hoard body or bar produced by the mold of Figs.15 to 19.

Fig. 21 is a view in longitudinal section through the closed moldsections constituting the mold for overmolding the frets on the board ofFigs. 16 and 20, the mold being shown in closed position at thecompletion fret overmolding operation with the completed fretted fingerboard therein.

Fig. 22 is a longitudinal section through the closed mold and itscontained finger board of Fig. 21, but taken along the longitudinalcenter of the mold.

Fig. 23 is a view in transverse section through the closed mold of Figs.21 and 22, taken as on the line 2323 of Fig. 21.

Fig. 24 is a transverse sectional view similar to Fig. 23, but taken ason the line 2424.

Fig. 25 is a fragmentary View in plan of a portion of the mold cavity ofthe under surface forming mold section of the fret mold of Figs. 21 to24.

Fig. 26 is a perspective view taken from the underside of the completed,modified form of finger board showing the solid runner or spine and thefret bonding ribs thereon.

As an example of a stringed musical instrument of the fretted fingerboard type, I have selected a ukulele for purposes of illustratin andexplaining the various features of an allplastic fretted finger board ofmy invention as adapted to and embodied in such example instrument.While an all plastic finger board of the invention is particularlyadapted to embodiment in stringed musical instruments formed of moldedthermoplastic materials, such as disclosed and claimed in my U. S.patent application filed May 15, 1950, Serial No. 149,741, now PatentNo. 2,597,154, it is to be understood, however, that the use of fingerboards of this invention is not restricted to such types of plasticinstruments, but is also intended for and adapted to use with any of thestringed musical instruments of the wood or other material forms.Further, finger boards of the invention are not limited or restricted toembodiment in and use with stringed musical instruments of the ukuleletype, but are adapted and intended for use as to all or any of thefeatures thereof, with stringed musical instruments requiring or capableof using a fretted finger board, such for example as all of the typesand. forms of guitars, banjos, mandolins and such like instruments.

The example instrument may be considered. to be a ukulele formed ofplastic materials, and, referring now to Figs. 1 and 2, includes thebody B of standard shape and plan form with a neck N extending from oneend thereof to terminate in an inclined head H which mounts the usualstring tuning keys or pegs P-I, P-2, P-3 and P4. The body B includes atthe forward or front side thereof a sounding board S secured thereon andthereacross and having a sound opening R therethrough located inposition between the neck N of the body and a bridge T securedtransversely on and being located at the outer side of the soundingboard S. The body B with sounding board S thus provides a resonant bodyor bell, and both the body and the sounding board in this example may beconsidered to be formed of a polystyrene plastic with the sounding boardand the walls of the body each formed of a thickness of the order ofapproximately eight-hundredths of an inch (.08")

A musical instrument of the ukulele type is provided, in itsconventional or usual forms with four (4) strings, constituting a Bstring, an Ft string, a D string, and an A string. In the exampleinstrument the four (4) strings are identified by the referencecharacters I, 2, 3, and 4, in the usual numbering order across theinstrument, with string No. 1 being the B string. string No. 2 the Ftstring, string No; 3 the D string, and string No. 4 the A string. Theukulele is a type of instrument utilizing a fretted fingerboard, and inthe example instrument hereof, a fretted finger board produced by themethod and embodying the structural and functional features of theinvention, is mounted in position in the usual location on and over theouter side of the neck N extending between the adjacent end of body Band the inner end of the head H. In this instance, the finger board issuitably secured, as by cementing, on the outer side of the neck and isheld against lateral displacement by suitable structural, longitudinalside flanges or lugs as will be hereinafter referred to more in detail.Thus mounted, the strings I, 2, 3 and 4 which are connected at theirouter ends to the tuning keys Pl, P2, P3 and P4, respectively, and attheir inner ends to the bridge T, extend longitudinally over andinwardly along and across the finger board 20.

The bridge T to which the inner ends of the strings are releasablysecured, provides extended outwardly therefrom a contact bar or strip 5across which the strings are stretched in contact therewith, so thatthis bar 5 provides a straight line contact edge at and engaged by theinner end portions of the strings which extend thereacross. Inaccordance with a feature of my invention to be referred to more indetail hereinafter, the finger board 20 is provided at its outer end inimmediate proximity to the inner side of the nut or string. divider 2!with a master fret MF which is extended thereacross and which provides astraight line outer edge contact surface across which the strings 2, 3and are stretched in constant engagement therewith. Thus, the distancebetween the longitudinal center of the straight line contact edge ofmaster fret MF and the longitudinal center of the straight line contactedge of the contact bar or strip 5 on the bridge T determines themaximum effective vibratory lengths of the strings I, 2, 3

and 4, with these strings in mounted positions stretched between thetuning pegs on the head H and the bridge T on the sounding board S orbody of the instrument. The distance between the string contact edge ofbridge contact bar 5 and the contact edge of the master fret MF isdetermined and established with close tolerances and forms the basingdistance factor in accordance with my invention, in the determination ofthe precision spacing of the series of frets on the fret bar 20, betweenthe master fret MF and the last or innermost fret on the finger board.

In the ukulele of the example thereof, the body B, including thesounding board S, has its greatest length longitudinally or along theaxis of the instrument, equal to approximately 8.504, while the overallaxial distance between the outer end of the body B and the extreme outerend of the head H is approximately 20.10". The maximum depth orthickness of the body B is approximately 2", while the maximumtransverse width at the portion of the body between the sound opening Rand the outer end of the body is approximately 6". The distance betweenthe effective contact edge of contact bar 5 of bridge T and theeffective contact edge of master fret MF of the fingerboard 2B, whichdetermines and fixes the maximum vibratory length of the strings I, 2, 3and 4, is in the example instrument, approximately 13.932".

The bridge T, referring to Fig. 1, provides at the outer side thereofspaced outwardly from contact bar 5, the series of spaced stringreceiving slots Ia, 2a, 3a and 4a with the adjacent slots of the seriesbeing spaced apart approximately T". The nut or string divider 2i of thefinger board 20 of my invention is provided with string receiving slotsor grooves 21a, 21b, He, and 21d, for maintaining the spacing of thestrings as they pass from the master fret MF to the tuning pegs on thehead H (see Fig. '3). These string receiving slots of the nut 2| are inthis instance spaced apart across the nut with slot 2Ib spaced from slot21a a distance equal to approximately .375"; slot 2|c spaced from slot2Ib a distance approximately equal to .374"; and slot 2H1 spaced fromslot 2|c a distance approximately equal to .375

The finger board 2!] of the form of Figs. 1 to 14, comprises a generallyrectangular body or bar member 22, referring now to Fig. 3 of thedrawings, which provides at its outer side a fiat, smooth face orsurface 2211 on and across which a series of frets are transverselydisposed in positions spaced apart longitudinally of the board. In thestandard ukulele instrument a series of twelve (12) basic frets isprovided between the string engaged contact member, such as the masterfret MF of the example, at the outer end of the finger board, and theinner end of the board adjacent the body B. These twelve (12) basicfrets are spaced apart inwardly from the outer end of the boardprogressively decreased distances, so that the twelve (12) spaces formedalong the board at the rear of the twelve (12) 7 therefore, to obtainthe most eflicient and more nearly perfect musical results from aninstrument it is essential that the frets have the most preciselocations and spacings relative to each other and to and along the fixedmaximum vibratory lengths of the strings.

I have developed and produced a system and definite arrangement ofspacing for the frets of the finger board of a stringed musicalinstrument, and I have applied and exemplified this spacing system inthe example ukulele instrument, both for the twelve (12) basic frets ofSu an instrument, and for the additional frets provided by the fingerboard extension of the form of Figs. 1 to 3 of my present invention.

The finger board 20, of this example, provides projecting from andacross the outer surface 22a thereof, the series of twelve (12) basicfrets Fl, F2, F3, F4, F5, F6, Fl, F3, F9, Fl0, Fll and Fl2, and on theextension 23 of the finger board 20, the series of additional frets FlS,Fld, F15, Flfi and Flll, projecting from and across the flat outersurface 23a of the extension 23. The distance between the longitudinalcenters of the master fret MF and the string contact bar 5 of bridge T,which distance determines the effective string lengths, is in thisexample instrument, 13.8070". The fret Fl2 located at the inner end ofthe main finger board body 22 adjacent the extension 23, is positionedin accordance with y invention, on the finger board with itslongitudinal center spaced from the longitudinal center of the masterfret MF at the outer end of the finger board, a distance equal to6.9035, that is, one-half the effective string length. In this distancethe remaining eleven (11) basic frets are spaced apart progressivelydecreasing distances inwardly from the master fret MF, and in accordancewith my invention, the spacing between the longitudinal centers of thesefrets is as follows:

Inches MP to Fl .77499 Fl to F2 .73148 F2 to F3 69043 F3 to F l 65168 F4to F5 61510 F5 to F5 58057 F6 to F'l 54799 F! to F8 51722 F8 to F9 48819F9 to Fl' .46079 Fit! to PM .43492 Fll' to F12 .41051 The spacingsbetween the additional frets Fl3 through Fl'l, of the extension 23 ofthe finger board 20, progressively decrease inwardly of the extension,and these spacings, measured between the longitudinal centers of theadditional frets, are as follows:

. Inches Fl2 to Flt .38750 Fl3 to Fl l .36574 FM to Fl 34522 Fl5 to Flt32584 FIG to Fl'l 30755 By this system and arrangement of ukulele fingerboard fret spacing, it is a characteristic of the spacings that thespacing between the first additional fret Flt of the board extension 23and the last or innermost fret Flz of the series of basic frets, equalsone-half the distance of the spacing between the outermost pair of fretson board 20; that is, between the fret Fl and the master fret MF: andthat each succeeding spac-. ing between the additional frets Onextension 23 equals one-half A?) of each succeeding spacing betweenbasic frets inwardly of the finger board. Thus, the spacing betweenfrets FL; and FM equals one-half /2) the spacing between frets Fl andF2; the spacing between frets FM and Fl 5 equals one-half /2) thespacing between frets F2 and F3; the spacing between frets Fl5 and FIGequals one-half the spacing bebetween frets F3 and F4; and the spacingbetween frets Flfi and FH equals one-ha1f the spacing between frets F4and F5. If, as is contemplated by and included within the scope of theinvention, the extension 23 of the finger board 20 is increased inlength and provided with additional frets inwardly thereof, this sameprogressive spacing relationship between the a ditional frets and thebasic frets would be carried out in accordance with the Spacing systemand arrangement of my invention.

With respect to the progressively decreasing spacing between the twelve12) basic frets, inwardly of the finger board 20, it is to be noted thatthe increments of decrease constantly become smaller. Within thepractical limits of production the mathematically exact figures arerounded off at five decimals, otherwise it would be necessary to workwith impractical figures carried out to ten, twenty or more decimals.

The fret spacings in accordance with my nvention are computed anddetermined as follows:

Identifying the twelve (12) intervals or spacings between the series ofbasic frets lVIF through Fl2, as a1, a2. a3, (14, as, as, at, as, as,are, G11, G12, the ratio between each note of the twelve (12) notesproduced therefrom is such that repeated twelve (12) times it doublesthe frequency, or halves the length, or

r giving Consider the distance between MF and bar 5 of the bridge T (seeFigs. 1 and 2), or open string length as L, then the string length ordistance between MF and Fl2=L/2.

If the fret spacings from MF to Fl 2 are known, then the fret spacingsfrom Fl2 to 5 will be exactly half as large as the correspondingspacings from MF to Fl2.

Thus, it is only necessary to compute the twelve (12) fret spacings fromMF to FIZ.

1 ince the sum of all the fret spacings between MF and Fl2 must equalL/2 and the sum of a geometric series is given by it follows that thefret spacings may be computed for any string of open length L, by theformula:

lan:.0561256L (.9438744) where n denotes the number of the fret spacingsdesired starting from MF.

As the string length L of the example instrument is 13.8070" then byusing the above formula, the fret spacings for the example instrumentwill be determined to be as hereinbefore listed.

It is to be noted that (L1 is to L exactly as a2 is to La1. That is tosay, that the first fret spacing is always the same fraction of thewhole open string length considered or, since ,a1=.05613 open string,then if (11 is subtracted from open string length, 0.2 is the samefraction of what is left.

For example, when L=13.807,

a1=.77491=.056125 13.807 La1=13.807-.'77491 13.032l

then

The two numbers in the formula are complements of each other, that is,they add up to 1, since In accordance with the invention the formula maybe used in one or other of the following In the formula of any of theabove forms, if L is the length of the open string on any frettedinstrument then the width of the n fret space is given by the formula.While it is only necessary to compute the first twelve (12) basic fretintervals or spaces, as the ones higher up are sub-multiples of thefirst twelve (12), yet the formula will apply equally well to the fretsof higher numbers than 12. It is merely necessary to make 11. the fretnumber desired whether it be the 17th or the 30th, or any other.

For practical purposes the figures hereinabove given may be consideredto be critical for the example finger board of the specified dimensions,through three (3) decimals or to thousandths of an inch with a toleranceof one thousandth of an inch (.001). Hence, any deviations inmathematical exactitude in the figures given is without materialsignificance within such a tolerance, and is due to the arbitraryrounding off or reduction to four (4) or to five (5) decimals, of themathematically exact figures resulting from the computations with theformulae given by the invention.

It is to be understood that the fret spacing system of my invention, ashereinbefore described and explained, is not in any sense limited to 10adaptation and use with the all-plastic finger board formin anotherfeature of my present invention. Such spacing may be effectively andefiiciently utilized for positioning the standard or conventional fretforming metal, or other material strips which are inset into position onand across a wood or other material finger board phase of my invention,two forms of all-plastic finger boards particularly adapted for theukulele type of musical instrument. Essentially, such an all-plasticfinger board of the invention is characterized by a plastic materialfinger board body or bar across the outer side of which are overmolded,either as complete over molds across the outer surface of the board, oras partially inset or inlaid into the board, a series of plastic fretsformed of a plastic material, preferably having certain differentcharacteristics from those of the .body forming plastic and being of acolor contrasting with the color of the body.

The finger board 20 of Figs. 1 to 14, is an example of one form of boardof the invention provided with an additional fret carrying extension 23and having the frets overmolded on and partially inset or inlaid in thematerial of the board body and the extension thereof.

Referring to Figs. 1, 2 and 3 in particular, the finger board 20comprises the body or fiat bar member 22 which is injection molded orotherwise suitably formed from a thermoplastic material which in thisexample is a polystyrene plastic, preferably pigmented to have arelative dark color, say a mahogany color. The polystyrene utilized forthe board body preferably has the following characteristics:

Tensile strength, A, bar, p. s. i 5500-6500 Elongation, percent 1.4-2.0Modulus in tension l05 p. s. i 4.3-4.7 Impact strength:

Izod notches, bar, ft.

lbs/in. of notch 0.3-0.6 Izod unnotches, A bar, ft.

lbs/in. of width 2-6 Flexural strength, A" bar, p. s. i 12,000-15,000Heat distortion, A," bar, "F 164-168 Flammability, in./min 1 Rockwellhardness M68-80 Specific gravity 1.05-1.07 Dielectric constant:

60 cycles 2.45-2.55 10 cycles 2.45-2.55 Power factor:

60 cycles 00001-00003 10 cycles 00001-00004 For the example instrument,the finger board 20 formed of the indicated polystyrene plastic, has thenut or string divider 2| molded or formed integral therewith on andacross the outer end thereof. At the opposite or inner end the main body22 of the finger board is extended inwardly from the innermost fret Fl 2of the series of basic frets, to provide the extension 23 which hasformed thereon the series of additional frets Fl2 to Fl 1, inclusive.The outer or finger side of the finger board 20, when the ukuleleinstrument of the example is being held in playing position by a player,is constituted in this example by the longitudinal edge 24 of the boardwhich extends from the nut 21 to the extreme inner end of the extension23. The opposite or inner longitudinal edge 25 of the board isterminated at its inner end at a location intermediate the spacingbetween innermost basic fret FIZ and the outermost or first additionalfret F13. The inner longitudinal edge of the extension 23 is ofdecreasing width inwardly of the extension, so that this edge follows ageneral inward and outward inclination across the board, the edge beingof scalloped form comprising consecutive arcuate recesses 25 joined byprojecting portions 26a with the recesses being opposite the inner endsof the additional frets on the extension 23 respectively adjacentthereto. This construction and conformation of the inner longitudinaledge of the finger board extension 23 will be clear by reference to Fig.3.

The nut or string divider 2| formed or molded integral with the board 22at the outer end thereof is formed with the string spacing slots 21a,Zlb, Ho and 21d, each of which has a depth to extend below a planeparallel with the face 22a of the board and passing through the outerstring contact edge of the master fret MF, so that, in

assembled position of the finger board on the neck end of theinstrument, and with the strings I, 2, 3 and i in operative positionstretched between bridge T and the tuning pegs, the Strings have onlycontact with the master fret MF. Thus, the nut or string divider 2ifunctions solely to maintain the lateral spacing between the strings andis not normally contacted or engaged by the strings.

This integral nut or string divider 21, in the example hereof, is alsoformed to function as a positioning member for the outer end of thefinger board 20. To this end nut 2! is formed of a depth to provide aflange portion 21c which extends transversely across the finger board 20and projects inwardly therefrom at the outer end thereof for seating ina suitable recess or seat 21 (see Fig. 2) of the neck N when the fingerboard is in assembled, secured position in the instrument.

The overall length of the extension providing form of finger board 20 ofFig. 3, for the example instrument of Figs. 1 and 2, is approximately8.15", while the length of that portion of the board which mounts thetwelve (12) basic frets FE to F12, inclusive, may be taken to beapproximately 7.50. The width of the finger board 20 at its outer end,that is to say, the width of the nut 21 is approximately 35.6 mm.; themaximum width of the board on a transverse dimension at the position offret i2 is approximately 46.7 mm.; and the width of the innermost end ofthe extension 23 of the finger board 20 is approximately 12 mm.

Preferably, as in the example of extended finger board 20, the extension23 has a thickness less than the thickness of the main portion of theboard body, as will be clear by reference to the completed finger board20 as it is shown in the fret overmolding mold of Figs. 11 and 12. Inthis instance, the thickness of the main portion of the body of theboard is 4.6 mm., while the thickness of the extension 23 is 2.2 mm.There is thus formed a shoulder 21 at the under side of board 20extending transversely thereacross and which serves to engage and seatagainst the 12 adjacent outer side of the end wall of the body B andadjacent structure of neck N, when the finger board is in assembledposition in the instrument. In assembled position the extension 23extends inwardly on and across the outer side surface of the soundingboard S, as is clearly shown in Figs. 1 and 2 of the drawings. Thus, insuch assembled position the additional frets Fit to Fll of the extension23 are located below the strings I, 2, 3 and 4, but with no one of theseadditional frets extending to and beneath string No. 4, the A string.The first additional fret F13 extends beneath strings I, 2 and 3; theadditional frets FM and FIE extend beneath strings i and 2, whileadditional frets F16 and F11 extend only beneath string No. 1, the Bstring.

The underside of the main body 22 of finger board 20 is provided withthe opposite, longitudinal flanges 25 extending therealong but spacedinwardly slight distances from the adjacent inner and outer longitudinaledges 24 and 25, respectively, of the board body. There is thus formedat the under side of the body along the opposite longitudinal edgesthereof the seating shoulders 28a for seating on and cementing to thecomplementary opposite outer edges respectively, of the opposite sidewalls of the neck end (see Fig. 2). In assembled position of the fingerboard 2%] on the neck N, the flanges 23, extend inwardly into the neckat and are engaged against the adjacent inner side walls thereof to thuspositively position the finger board on the neck against lateraldisplacement. The under side flanges '28 and the seating shoulders 28aformed thereby, are clearly shown in the completed finger board as it isshown in the mold of Figs. 11, 12, 13 and 14.

Each of the twelve (12) basic frets Fl to P12, inclusive, and each ofthe additional frets F13 to Fll, inclusive, is formed of a metallicpolystyrene plastic having metallic characteristics and particularlyhaving the characteristic of .a metal in appearance and of a contrastingcolor to the color of the finished material of which the board body 22is formed. In this example, the fret forming material is a polystyreneplastic to which has been added a metallic powder, say for example amixture of aluminum powder and copper powder, to form a plastic mixtureof which the metallic powder mixture constitutes approximately 5% to20%. Such polystyrene is preferably of the natural colorless crystalform and when metallized with the aluminum and copper, the resultingplastic has a silvery or copper-like color.

The polystyrene utilized for metallizing with the metal powder has thefollowing characteristics:

Tensile strength, bar, p. s. i 6000-6500 Elongation, percent 1.4-2.0Modulus in Tension p. s. i 4.3-4.7 Impact strength:

Izod notches, bar, ft.

lbs/in. of notch 0.3-0.6 Izod unnotches, A;" bar, .ft.

lbs/in. of width 2-6 Flexural strength, A; bar, p. s. i 12,000-15,000

Heat distortion, A;" bar, F 168-175 Flammability, in./min 1 Rockwellhardness 1468-78 Specific gravity 1.05-1.07 Dielectric constant:

60 cycles 2.45-2.55 10 cycles 2.45-2.55

13 Power factor:

60 cycles 0.00010.0003 cycles 0.00010.0004

In the form of finger board 20, as shown in Figs. 1 to 14, all the fretsincluding the master fret MF, are formed on and across and projectingoutwardly from the outer side or face 22a of the body 22, and each ispartially inset or inlaid into suitable grooves 30 formed in and acrossthe outer side 2211 of the board body 22, and each is suitably bondedand secured to the board body so as to form therewith what is in effecta one-piece, integral structure, with the frets being of a contrastingcolor to the color of the board body, as hereinbefore described. Theinset or partially inlaid construction and formation of the frets in theboard body will be clear by reference to Figs. 11 to 14, showing thecompleted, fretted finger board 20 in the fret over molding mold beforeremoval therefrom. In this particular example, the master fret MF has athickness at the exterior of face 22a of board body 22, of .030", thatis, fret MF projects that distance from the outer surface 22a of theboard. Each of the remaining frets Fl to Fl'l, inclusive, projectsoutwardly or has an external thickness of 0.25", so that, when thestrings I, 2, 3 and 4 are in position extended over the finger board 20between bridge T and the tuning pegs on head H, the strings are normallyheld out of engagement or contact with the frets Fl to Fl 1, inclusive,as will be clear by reference to Fig. 2 of the drawings.

Each of the frets extends substantially completely across the width ofthe board body 22 at the location of that fret, but each fret terminatesat its opposite ends spaced inwardly from the adjacent side edges,respectively, of the finger board body, such spacing in this instancebeing of the order of /64- of an inch. The opposite ends of each fretare rounded, which together with the inward spacing of the fret endspermits of a player sliding his fingers from one fret to anothersmoothly and without encountering rough or abruptly edged structure.

A completed finger board forming body 22 and its extension 23, prior tothe overmolding of the frets thereon, is shown in top plan view in Fig.10, and in longitudinal sectional views in Figs, 5 and 6. In Fig. 10,the body is shown in position in one of the mold sections of the moldfor overmolding the frets thereon, while in Figs. 5 and 6, the board isshown in completed condition in the board body forming mold prior toopening of the latter and removal of the completed body 22. Referring toFig. 10, the completed board body 22 has the transverse fret inlaying orreceiving grooves 36 formed therein across the outer side thereof inproper spacing to space the frets therein in accordance with the spacingarrangement of the invention. Each of these grooves 30 has a series ofspaced feed and bond forming holes 31 opening into the bottom of thegroove and extending through the board body 22 to the under sidethereof.

In the completed, fretted finger board 20 referring now to Figs. 11through 14, the master fret MF and the frets Fl to Fl'l, inclusive, areover-molded onto the board 22 and partially inset or inlaid relative tothe board in the grooves 30, respectively. Each of the frets is bondedand tightly keyed and secured on and to the board and in the grooves31], by bonds or sprues 32 formed by the portions of the fret formingplastic extended through and set in the feed or bonding holes 3i. Thus,each fret becomes in effect a part of the board, so that, for allpractical uses and under all the loads to which the frets will benormally subjected, the board frets and their bonds become a monolithicor integral one-piece structure, but formed of thermoplastic materialshaving contrasting color and certain differences in physicalcharacteristics.

The invention provides in addition to the bonds 32 for the frets, afurther system of bonding at the under or inner side of the body 22, andutilizes for this bonding system the material in the runners by whichthe mold feeds and supplies the thermoplastic material under pressureinto all the mold cavities. Referring to Figs. 5 through 10, in themolding of the finger board body 22 there is formed at the under side ofthe body along the longitudinal center or axis thereof and extendingthroughout the length of the board, a channel or groove 40. Thi runnerat the inner end of the main body 22 of the board is continued as aninclined section ll which extends longitudinally of the underside of theextension 23. A series of rib-forming grooves 44 are formed disposedtransversely across the under side of the board body 22 and extension 23with their longitudinal axes lying in the plane passing through thelongitudinal axes of the fret forming grooves 3%, respectively, at theouter side of the board body. These underside rib forming grooves 44extend transversely across, open into and receive fret-forming materialfrom the central runner 453. The rib-forming grooves 44 are sub--stantially co-extensive in length with their corresponding grooves 39,respectively, at the outer side of the board body and the fret groovesupply holes 3| open into these underside rib-forming supply grooves 44,so that there are formed flow paths from the central runner 40 throughgrooves 44 and holes 3|, to the fret-forming grooves 30 at the outerside of the board body. It is to be noted that in the preferred form ofthis example, the central runner or channel 40 along the main portion ofthe body 22 has a greater depth inwardly than the depths of theunderside rib-forming channels 44 which open thereinto and receivefret-forming plastic therefrom, and these relative depths may apply tothe runner section 4| and the rib-forming grooves 44 at the under sideof the extension 23 of the finger board, or the depth of runner M maynot exceed that of grooves 43, whichever relative depths may be foundpreferable.

In the completed, fretted finger board a central stem or spine 45 ofmetallic fret-forming plastic is completely inlaid into and along therunner or channel 4lltl at the underside of the board 2! with a seriesof transverse branches or ribs 45 completely inlaid into the body andextending from the spine, across the underside of the board and bondedthrough the board to the fret overmolded at the outer side thereof bythe bond or sprues 32 formed by and set in the holes 3l. In this form ofthe invention a spine 45 and ribs 46 are completely inlaid with theirouter surfaces flush with the underside of the body. There is thusprovided an integrated bonding system at and along the under side of theboard to which the frets at the outer side of the board are attached andbonded, and this under side bonding system not only results in effectivebonding of the frets but also functions to stiffen the completed fingerboard against twisting or distortion, so that a very rigidboard-structure results.

The finger board 20 may also include, if desired,

a series of markers K in the form of disks inlaid at the desiredpositions between frets along the longitudinal center or axis of theboard and having their outer surfaces flush with the outer surface 22Aof the board. These markers K, in this instance, happen to be five innumber, but the invention is in no sense limited to this or anyparticular number of such markers, or to the frets between which theymay be located. Each marker is formed from the metallic plastic materialof which the frets are formed and thus have a color contrasting with thecolor of the body of the board, such color being in this example asilver or aluminum shade with the body of the board a dark mahoganycolor. These markers are formed as inlays in bores ii, referrin now toFig. 10, which are formed through the board body 22 in the molding ofthat body, and each bore opens into and is adapted to receive markerforming material from the supply of fret forming material in the runnerii at the under side of the board body.

Instead of the frets being partially inset or inlaid in grooves such asthe grooves 38 formed in and across the outer side of the board body,the frets may be formed on and across the outer side of the body ascomplete cvermolds on the body outer surface, while bein bonded to thebody and to the bonding system at the under side of the body by bonds orsprues 32. An allplastic finger board having the master fret MF and thetwelve (12) basic frets Fl to FIE, inclusive, formed as completeovermolds on the outer surface of modified form of finger board 26', is

illustrated, together with the molds for forming the same, in Figs. 15to of the drawings.

In the form of finger board 28', the fret extension such as extension 23of fingerboard 28, is eliminated, so that the board merely extends inassembled position to an inner end fiange portion 23 adapted to fit overthe adjacent outer side of the sounding board S of instrument body 13.At the under side of the board 26 the same fret bonding and boardstiffening system is employed that is described and explained inconnection with the finger board Ell of the form of Figs. 1 to 3, suchsystem including at the under side of board 20 the central spine withthe transverse fret bonding ribs it. In the form of finger board 28',the bonding system of spine and ribs are not inset or inlaid in theunder side of the board but are provided as complete overmolds onto suchunder side. The completely overmolded frets ME and F! to Fit, inclusive,on the outer side of finger board 2B are bonded and keyed to thecompletely overmolded bonding system at the under side of the board, bythe bonds or sprues 32 which connect integrally the frets and bondingribs through the bond forming holes 3!, similar to such holes asprovided for the finger body 20.

The form of finger board 23 is further modified from the form of thefinger board 26, in that the integral nut or string divider M is notmolded as an integral part of and positioned across the outer end of theboard. With the board of the form of Fig. 20, a separate string divideror strip is provided similar to divider 2!, which separate divider isseated and secured in the end of the neck N of the instrument in properposition at the outer end of the finger board. Such separate divider isprovided with string receiving slots similar to the slots of divider 2l, which-will pass the strings therethrough in proper spacinwhile'permitting the strings to engage solely at their outer 16 endlengths with and on the master fret MI.

The finger board .20 instead of being provided with the mounting andpositioning flanges 28 of the form of finger board to has the oppositelongitudinal side flanges 28 at the under side thereof to provide bytheir inner edges seating surfaces for fitting down on the outer edgesof the opposite sides, respectively, of the neck N. A series of spacedinwardly projecting mounting and positioning lugs 29 are provided inconjunction with flanges 28, in positions projecting inwardly from theunder side of the board along the inner side of each of the flanges. Thepositioning lugs 29 are of greater depth than and project inwardly fromthe inner side of that fiange 28' with which associated, and, in thisinstance, are located in positions between the series of bonding ribsit: at the underside of the board. However, this form of the inventionis not limited to any particular number, spacing or positioning of thelugs 29. A lesser number than that disclosed herein may be utilized withthe lugs being provided only between alternate pairs of bonding ribs it,or in other spacing arrange ments. The function of the lugs 23 is thesame as that of the positioning flanges 28 of the finger board 20.

By my invention I have devised a method for forming all-plastic frettedfinger boards embodying the features and characteristics of theinvention hereinbefore described and explained, by which method themetallized plastic frets on the outer side of the board, the fretbonding and board strengthening system of ribs at the under side of theboard, and the position markers in the board, are overmolded in eithercomplete overlay or overmold, or as being partially inlaid or inset inthe body of the board. By my method I first form, preferably byinjection molding, the body of the finger board and then by a separateinjection molding operation in a separate mold, .I overmold or overlaythe frets on and across the outer side of the board body and the fretbonding system at the under side of the body, with the frets keyed orbonded through the board integrally with the bonding system. Further, incarrying out this method I utilize a thermoplastic material, such as thepolystyrene having the characteristics of the example hereof, in whichthe melting point is lower than the melting point of the metallizedplastic utilized for forming the frets, the bonding ribs and positionmarkers, so that, there results a further bonding or welding between themetallized plastic and the plastic of the board body.

I have shown, more or less schematically, in Figs. 4 to 14 inclusive,the, finger board body forming injection mold and the separate, fretoverlaying or overmolding injection mold, for the form of finger board28 of Figs. 1 to 3. These molds .as schematically shown may be taken tobe molds of the general character familiar in the art of injectionmolding.

In Figs. 4 to 9, are shown the mold for forming therein as a separatecomponent the board body .22 for the finger board as. This mold includes.a mold section 58 and a mating section 5|. The mold cavity of sectionas for forming the under side of the mold body 22 is shown in Fig. 4,and includes: the main bottom surface 56a with the section 5% extendedat one end thereof of less depth than section Eda and having thescalloped edge tile for forming extension 23; the raised, longitudinalrib 52 for forming the longitudinal channel or runner in in the underside of the body, together with the reduced thickness inclined section52' of the rib 52 along surface 500 for forming the section 4| of therunner at the under side of the board extension 23; the transverse ribs53 for forming bonding rib inlaying grooves 44; the transverse channel54 across one end of the mold cavity for forming the flange 252 of theintegral nut or string divider 2| of board 20; and the oppositelongitudinal side grooves 55 for forming the positioning flanges 28 atthe underside of the board. In addition, the mold section 50 mayinclude; the series of core pins 56 for forming through board body 22,the feed holes or gates 3| by which the metallized plastic is fed fromthe runner 40 through the grooves 44 to the fret forming grooves 30 atthe outer side of the board body; the core pins 57 for forming the holesor bores 41 in which the markers K are formed; and a series of lmock-outpins 58 in accordance with usual injection mold practice.

The mold section 5| which forms the outer side of the board provides,referring now to Figs. 5 and 6, the series of transverse parallel ribs59 thereacross spaced apart longitudinally of the mold cavity to formacross the outer side of the board 20, the fret inlaying grooves 35).The mold section 5| also includes transversely across one end of themold forming cavity, the channel 60 for forming integrally with theboard body the nut or string divider 2!. The injection inlet or sprueopening for the mold 50-5! may be provided at any suitable location, butin this instance may be taken to be located at the left-hand end of themold as viewed in Figs. 5 and 6, so that, the board forming plastic isinjected under pressure at the nut or string divider end of the moldcavity.

Thus, in carrying out the first step of my method, the finger board bodyfor the all-plastic, fretted finger board of Figs. 1 to 3, is firstmolded as a separate component in the mold 50-5l, by injecting into themold and distributing therethrough under pressure, the polystyreneplastic having the characteristics hereinbefore given for such bodyforming plastic. The body forming plastic i suitably pigmented toprovide the desired color when molded, such as the dark mahogany colorhereinbefore specified.

With the polystyrene plastic of the herein defined characteristics theplastic has a melting point of between 360 F. to 380 F. and is injectedinto the mold 505l at a molding pressure within the range of 12,000 to15,000 pounds per square inch, and at a temperature of 480 F. to 520 F.

Upon completion in the mold 505l of the finger board body 22, the moldmay be opened and the completed board body knocked out or ejected in theusual manner. The completed board body is shown in Figs. 5 and 6 in themold preparatory to removal and to the carrying out of the next step ofovermolding the frets and their bonding on the board, in accordance withthe method of the invention.

The mold in which the fret overmolding and fingerboard completing stepof the invention is carried out, is shown in Figs. 10 to 14, ascomprising the mating mold sections it and It. The mold section 10 isformed to overmold the bonding spine 45 and the ribs 46 on the undersurface of the board body 22, while the section H when mated withsection H1 is formed to overmold on and across the outer surface 22a oflatter is mated with section 10 to close the mold.

Referring to Figs. 13 and 14 in particular, the mold cavity of moldsection 10 provides a flat, plane surface 72 against which is seated andpressed the under surface of the body 22, so that, the runner 40 and thetransverse bonding rib forming grooves 44 thereof are closed acrosstheir open sides. The mold cavity also provides the grooves or channels73 for receiving the positioning flanges 28 located along the oppositelongitudinal edges of the board, as well as providing a groove or cavity14 into which fits and tightly seats the flange 22a of the integral nut2! formed across the outer end of the board body. The mold cavity ofsection 10 for receiving a completed finger board body 22, is alsoformed with an end portion of less depth than the main portion of thecavity to provide the flat surface 72' to receive the extension 23 andclose the open sides of the runner section and the bonding rib grooves44, of the under side of the extension, as will be clear by reference toFigs. 11 and 12. One edge of the shallow cavity for receiving theextension 23 is formed with an edge 75 formed complementary to andreceiving and tightly fitting against the scalloped edge 2525c of theboard body 22.

The section II of mold 10'H, is formed to provide a mold cavity to fitover and receive the outer surface of the board body when section II ismated with section 10. The body receiving cavity of section ll providesa fiat, plane surface 16 which fits tightly onto and against the outerother surface 22a of body 22 and surface 23a of the extension 23, asclearly shown in Figs. 11 to 14. Fret forming grooves 11 are formed inand transversely across mold surface 16 for precise alignment with thecomplementary inlaying grooves 30 formed in and across the outer side22a of the body, as shown particularly in Fig. 13.

With a finger board body 22 inserted in the enclosed mold 10'H, themetallized fret forming plastic having a melting point in the range from400 F. to 430 F. is then injected into the channel or runner 40,preferably through an inlet or sprue opening at the left-hand end of themold when viewing Figs. 11 and 12. The injection of the metallizedplastic is carried out under a pressure in a range from 10,000 to 12,000pounds per square inch, and at a temperature preferably of the order of510 F. to 530 F. The fret forming plastic is thus forced through channel40 and is distributed therefrom through the grooves 44, and from grooves44 through the feed holes 31 into the fret forming cavities formed bythe sets of grooves 30'|'|, until the runner and all of the grooves andthe feed openings 3! between the grooves, are filled with plastic. Thus,there is overmolded on the board body 22 in partial inlay across theouter side of the finger board the master fret MF and the series offrets Fl to PH, and there is overmolded in complete inlay at the underside of the board, the bonding system comprised of the spine 45 19 andthe ribs 46, with the latter bonded and keyed through the board body tothe frets by the integral bonds or sprues 32. At the same time the boresare filled from the runner Ml with the metallized plastic to formtherein the completely inlaid position markers K. And, as the meltingpoint of the polystyrene plastic of which the body 22 is formed is lowerthan the melting point of the fret forming metallized plastic, there isa fusing or melting of the plastic of the finger board by the heatedmetallized plastic to thereby further bond the frets and their undersurface bonding spine and ribs, to the body of the board.

There is thus formed by these two (2) molding steps a complete fretted,all-plastic finger board in which the frets are formed of a metallizedplastic having a metallic appearance which in color contrasts sharplywith the color of the body of the board, and in which the frets havecertain different physical characteristics, yet are so bonded and joinedwith the board as to provide what is in effect a one-piece, integral,fretted, all-plastic finger board.

The form of finger board of the completely overmolded fret typeexemplified by the finger board 20 shown in Figs. to 25, is produced bythe same injection molding method as described above in producing thefinger board 29 0f the partially inlaid type of fret. A completed boardbody 22' is formed by injection molding in a mold comprising the moldsections at and 8|. The cavity provided by section 88 forms the underside of the body 22 and includes the recesses 29' for forming thepositioning lugs 29, but as the bonding spine 35 and ribs it at theunder side of the board 23 are formed as complete overmolds, the mainsurface area of the mold cavity is formed as a fiat, plane surface.Suitable core pins 33 are mounted and provided in and across the moldcavity of section 88 to provide the feed holes or gates M for supplyingmetallized plastic to form the frets at the outer side of the boardbody. Additional core pins 84 are also provided for forming the openings41 through the board in which the position markers may be formed.

Referring to Figs. through 24, the mold for overmolding on a body 22'the series of frets and bonding ribs to complete the finger board,comprises mold sections at and 9!. Mold section 90 provides a moldcavity within which there is formed the central channel or runner 92 andtransverse grooves 83 thereacross at spaced intervals therealong to formthe bonding ribs 45. The mold section 9! which receives the outer sideof board body 22 is formed with a series of fret overmolding grooves 96thereacross and spaced apart therealong. A finger board body 22' isplaced in the mold Elli-4 with the rows of feed holes 3| therethroughaligned with the aligned grooves 93-9 l, the mold is closed, andmetallized fret forming plastic is then injected under pressure in thechannel 92 at one end of the mold as more or less schematicallyindicated at the left hand end of Fig. 21 at the inlet or sprue opening95. Plastic is thus distributed through and fills channel 92, ribforming grooves 93, feed holes 3| and fret forming grooves 96, to formin the latter the frets MP and i to H, as complete overmolds on theouter side of the board, and to form on the under side of the board ascomplete overmolds the spine 5 and bonding ribs 46 with the frets keyedto such ribs by the bonds or sprues 32 formed in the feed openings 3i.As the metallic plastic used for forming the frets has a higher meltingpoint than the plastic used for forming the body 22, there will be afurther bonding or welding of the frets and bonds to the board body, ashereinbefore explained in connection with the molding of the fingerboard 20.

It will also be evident that various other changes, modifications,substitutions and eliminations might be resorted to without departingfrom the spirit and scope of my invention and, hence, I do not desire tolimit the invention in all respects to the exact and specificdisclosures of the example of the invention herein described, except asmay be required by specific intended limitations thereto included in anyof the appending claims.

What I claim is:

l. A fretted finger board for stringed musical instruments comprising, abody member of molded plastic material, said body member being formedwith a series of transversely disposed spaced rows of holestherethrough, frets of plastic material positioned on said body memberalong said rows of holes, respectively, and sprues of the plasticmaterial of each fret being extended into the row of holes in said bodymember for such fret to bond the fret to the body member.

2. An allplastic, fretted finger board for stringed musical instrumentscomprised of, a body member of molded plastic material, a series offrets formed of plastic material positioned on and. transversely acrossthe outerside of said body member, a series of bonding ribs formed ofplastic material positioned on and transversely of the under side ofsaid body member, and a series of sprues of plastic material extendingthrough said body member and integrally connecting said frets with saidbonding ribs to bond said frets into fixed positions on said bodymember.

3. An all-plastic, fretted finger board comprised of, a molded plasticbody member formed with a series of transversely disposed rows of holestherethrough, said rows being spaced apart longitudinally along the bodymember, frets of plastic material positioned on and across the outerside of said body member along said rows of holes, respectively, aseries of transversely disposed plastic bonding ribs positioned on theunder side of said body member along said rows of holes, respectively,and sprues of plastic material extending through the holes of each rowan integrally bonding the frets to the ribs, respectively.

4. A fretted finger board for stringed musical instruments comprising, abody member of molded plastic material having in the outer side thereofa series of transversely disposed fret inlaying grooves therein spacedapart longitudinally thereof, said body member being provided with holestherethrough opening into said inlaying grooves, frets of molded plasticmaterial on and across the outer side of said body member in positionspartially inlaid in said grooves, respectively, and sprues of saidfret-forming plastic material being extended into said holes,respectively, to bond said frets to said body member.

5. An all plastic, fretted finger board comprismg a body member ofmolded plastic material, a string divider formed integrally with anddisposed transversely across the outer end of said body member, saidstring divider being extended outwardly yond the outer side of the bodymember and being provided with string receiving and spacing slotsthereacross, and said string divider being also extended outwardlybeyond the underside of said body to form a positioning flange formounting the finger board.

6. An all-plastic fretted finger board comprised of a body member ofplastic formed with a string divider integral therewith at and acrossthe outer end of said plastic body member, and a master fret as aseparate component molded onto and across the outer side of said bodymember and fixed thereto in rigid position thereon in immediateproximity to the inner side of said string divider.

7 An all-plastic fretted finger board comprising, a molded plastic bodymember formed with a string divider integral therewith disposedtransversely across the outer end thereof, said string divider beingformed with string spacing slots thereacross, a master fret molded as aseparat component secured in rigid position across the outer side of thesaid body member immediately adjacent the inner side of said stringdivider, a series of frets each formed of plastic molded as separatecomponents on and transversely across the outer side of said body memberin rigid positions thereon spaced apart longitudinally thereof betweensaid master fret and the inner end of said body member, and said masterfret being formed of a thickness to project from the outer side of saidbody a greater distance than the distance of projection from the outerside of the body of each of the remaining frets.

8. An all-plastic fretted finger board comprised of; a plastic bodymember formed with a series of transversely disposed rows of holestherethrough spaced apart longitudinally along the member, frets ofplastic material formed as separate components positioned on and acrossthe outer side of said body member over said rows of holes,respectively, a plastic material bonding spine at and disposedlongitudinally along the under side of said body member, a series oftransversely disposed bonding ribs of plastic material at the under sideof said body member extending across and being integrally joined withsaid bonding spine, and sprues of plastic material extended through theholes of each row of holes of said body member and being integrallyjoined with said frets and ribs to bond said frets into rigid positionson said body member.

9. The combination as defined in claim 8, in which the bonding spine andtransverse bonding ribs are completely inlaid into the under side of thebody member.

10. The combination as defined in claim 8, in which position markersintegral with and formed from material of said bonding spine are inlaidin said body member.

11. A fretted finger board for stringed musical instruments comprising,a body member of plastic material, frets of plastic material formed asseparate components positioned on said body member disposed transverselythereacross and spaced apart longitudinally therealong, said body memberbeing formed with holes therethrough, and sprues of plastic integralwith said frets extended into said holes of said body member to bondsaid frets to the body member.

12. An all-plastic fretted finger board comprising, in combination; aplastic string divider positioned disposed transversely across the outerend of said body member and being formed with string spacing slotstherein extending transversely therethrough; a master fret of plasticmaterial on said body member in position disposed transversely acrossthe outer side thereof immediately adjacent the inner side of saidstring divider; a series of frets formed of plastic material disposedtransversely across the outer side of said body member in positionsthereon spaced apart longitudinally thereof between said master fret andthe inner end of said body member; and said master fret being formed ofa thickness to project from the outer side of said body a greaterdistance than th distance of projection of each.

of the remaining frets constituting said series of frets on said bodymember.

MARIO MACCAFERRI.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,692,207 Hall Nov. 20, 1928 1,881,229 Young Oct. 4, 19322,086,493 Elingwood July 6, 1937 2,285,963 Gits et al June 9, 19422,337,550 Crosby Dec. 28, 1943 2,360,641 Bennett et al Oct. 1'7, 19442,489,408 Frost Nov. 29, 1949 2,492,845 Conkling et a1. Dec. 27, 19492,492,973 Dofsen et al. Jan. 3, 1950

